There are several species of bulrushes. Bulrushes are perennial grass-like plants and can grow to 10 feet tall in shallow water or in moist soils. Soft-stem bulrush can grow to 10 feet and grows in dense colonies from rhizomes. Soft-stem bulrush has a round (in cross section), light gray-green, relatively soft stem that comes to a point with no obvious leaves (only sheaths at the base of the stems). Flowers usually occur just below the tip of the stem.
Giant bulrush can also grow to 10 feet, is dark green with a hard, triangular stem and no obvious leaves (sheaths at the base of the stems).
Submerged portions of all aquatic plants provide habitats for many micro and macro invertebrates. These invertebrates in turn are used as food by fish and other wildlife species (e.g. amphibians, reptiles, ducks, etc.). After aquatic plants die, their decomposition by bacteria and fungi provides food (called “detritus”) for many aquatic invertebrates. Seeds of bulrushes are consumed by ducks and other birds while geese, muskrats, and nutria consume the rhizomes and early shoots.
Source: Aquaplant | Link source